The Bridges at Toko Ri
Talk about late to the party…
From what I’ve heard, in some circles, Pretty in Pink is considered a movie where evil wins.
Pretty Woman
One Flew Over the Cuckoo’s Nest
And regarding Cervaise’s idea to nominate movies that should have had a downer ending, I would like to say that every Frank Capra movie ever made would have been greatly improved by adding a scene where all the main players succomb to horrible deaths or somesuch.
Yes, that includes Zu Zu.
What’s that you say, Nurse Ratched? Is it time for my medication now?
Actually, I would say both endings of *Army of Darkness[\i] are bad. Even the ‘Hollywood’ ending has Ash confessing to a coworker that he didn’t say the incantation correctly which is (apparently) why a customer gets possessed and attacks him. If that one got through, who knows how much else evil has survived?! fact is, as smug as Ash looks in the end- he has the Hero’s Curse: He can’t go back to his old way of life no matter how he tries, every woman he ever falls in love with either dies and he he has to smash her to itty bits, or gets left behind. Humorously enough, he also can’t seem to *get it[\i] either; you don’t overcome challenges and difficulties by taking the most half-assed approach. And you sure as HELL don’t dare misspeak the words! 
On the commentary track of AoD, Bruce Campbell mentions the fact that he causes all this trouble because he can’t pay attention. He wasn’t listening to the ‘wizard’ explaining the words. He miscounted his sleeping potion drops because he heard a noise.
ADD will kill ya!